<?php

// This file is part of Moodle - http://moodle.org/
//
// Moodle is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Moodle is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.

/**
 * gdlib.php - Collection of routines in Moodle related to
 * processing images using GD
 *
 * @package   core
 * @copyright 1999 onwards Martin Dougiamas  {@link http://moodle.com}
 * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */

defined('MOODLE_INTERNAL') || die();

/**
 * Copies a rectangular portion of the source image to another rectangle in the destination image
 *
 * This function calls imagecopyresampled() if it is available and GD version is 2 at least.
 * Otherwise it reimplements the same behaviour. See the PHP manual page for more info.
 *
 * @link http://php.net/manual/en/function.imagecopyresampled.php
 * @param resource $dst_img the destination GD image resource
 * @param resource $src_img the source GD image resource
 * @param int $dst_x vthe X coordinate of the upper left corner in the destination image
 * @param int $dst_y the Y coordinate of the upper left corner in the destination image
 * @param int $src_x the X coordinate of the upper left corner in the source image
 * @param int $src_y the Y coordinate of the upper left corner in the source image
 * @param int $dst_w the width of the destination rectangle
 * @param int $dst_h the height of the destination rectangle
 * @param int $src_w the width of the source rectangle
 * @param int $src_h the height of the source rectangle
 * @return bool tru on success, false otherwise
 */
function imagecopybicubic($dst_img, $src_img, $dst_x, $dst_y, $src_x, $src_y, $dst_w, $dst_h, $src_w, $src_h) {
    global $CFG;

    if (function_exists('imagecopyresampled') and $CFG->gdversion >= 2) {
       return imagecopyresampled($dst_img, $src_img, $dst_x, $dst_y, $src_x, $src_y,
                                 $dst_w, $dst_h, $src_w, $src_h);
    }

    $totalcolors = imagecolorstotal($src_img);
    for ($i=0; $i<$totalcolors; $i++) {
        if ($colors = imagecolorsforindex($src_img, $i)) {
            imagecolorallocate($dst_img, $colors['red'], $colors['green'], $colors['blue']);
        }
    }

    $scalex = ($src_w - 1) / $dst_w;
    $scaley = ($src_h - 1) / $dst_h;

    $scalex2 = $scalex / 2.0;
    $scaley2 = $scaley / 2.0;

    for ($j = 0; $j < $dst_h; $j++) {
        $sy = $j * $scaley;

        for ($i = 0; $i < $dst_w; $i++) {
            $sx = $i * $scalex;

            $c1 = imagecolorsforindex($src_img, imagecolorat($src_img, (int)$sx, (int)$sy + $scaley2));
            $c2 = imagecolorsforindex($src_img, imagecolorat($src_img, (int)$sx, (int)$sy));
            $c3 = imagecolorsforindex($src_img, imagecolorat($src_img, (int)$sx + $scalex2, (int)$sy + $scaley2));
            $c4 = imagecolorsforindex($src_img, imagecolorat($src_img, (int)$sx + $scalex2, (int)$sy));

            $red = (int) (($c1['red'] + $c2['red'] + $c3['red'] + $c4['red']) / 4);
            $green = (int) (($c1['green'] + $c2['green'] + $c3['green'] + $c4['green']) / 4);
            $blue = (int) (($c1['blue'] + $c2['blue'] + $c3['blue'] + $c4['blue']) / 4);

            $color = imagecolorclosest($dst_img, $red, $green, $blue);
            imagesetpixel($dst_img, $i + $dst_x, $j + $dst_y, $color);
        }
    }
}

/**
 * Stores optimised icon images in icon file area
 *
 * @param context $context
 * @param string $component
 * @param string filearea
 * @param int $itemid
 * @param string $originalfile
 * @return mixed new unique revision number or false if not saved
 */
function process_new_icon($context, $component, $filearea, $itemid, $originalfile) {
    global $CFG;

    if (empty($CFG->gdversion)) {
        return false;
    }

    if (!is_file($originalfile)) {
        return false;
    }

    $imageinfo = getimagesize($originalfile);

    if (empty($imageinfo)) {
        return false;
    }

    $image = new stdClass();
    $image->width  = $imageinfo[0];
    $image->height = $imageinfo[1];
    $image->type   = $imageinfo[2];

    $t = null;
    switch ($image->type) {
        case IMAGETYPE_GIF:
            if (function_exists('imagecreatefromgif')) {
                $im = imagecreatefromgif($originalfile);
            } else {
                debugging('GIF not supported on this server');
                return false;
            }
            // Guess transparent colour from GIF.
            $transparent = imagecolortransparent($im);
            if ($transparent != -1) {
                $t = imagecolorsforindex($im, $transparent);
            }
            break;
        case IMAGETYPE_JPEG:
            if (function_exists('imagecreatefromjpeg')) {
                $im = imagecreatefromjpeg($originalfile);
            } else {
                debugging('JPEG not supported on this server');
                return false;
            }
            break;
        case IMAGETYPE_PNG:
            if (function_exists('imagecreatefrompng')) {
                $im = imagecreatefrompng($originalfile);
            } else {
                debugging('PNG not supported on this server');
                return false;
            }
            break;
        default:
            return false;
    }

    if (function_exists('imagepng')) {
        $imagefnc = 'imagepng';
        $imageext = '.png';
        $filters = PNG_NO_FILTER;
        $quality = 1;
    } else if (function_exists('imagejpeg')) {
        $imagefnc = 'imagejpeg';
        $imageext = '.jpg';
        $filters = null; // not used
        $quality = 90;
    } else {
        debugging('Jpeg and png not supported on this server, please fix server configuration');
        return false;
    }

    if (function_exists('imagecreatetruecolor') and $CFG->gdversion >= 2) {
        $im1 = imagecreatetruecolor(100, 100);
        $im2 = imagecreatetruecolor(35, 35);
        $im3 = imagecreatetruecolor(512, 512);
        if ($image->type != IMAGETYPE_JPEG and $imagefnc === 'imagepng') {
            if ($t) {
                // Transparent GIF hacking...
                $transparentcolour = imagecolorallocate($im1 , $t['red'] , $t['green'] , $t['blue']);
                imagecolortransparent($im1 , $transparentcolour);
                $transparentcolour = imagecolorallocate($im2 , $t['red'] , $t['green'] , $t['blue']);
                imagecolortransparent($im2 , $transparentcolour);
                $transparentcolour = imagecolorallocate($im3 , $t['red'] , $t['green'] , $t['blue']);
                imagecolortransparent($im3 , $transparentcolour);
            }

            imagealphablending($im1, false);
            $color = imagecolorallocatealpha($im1, 0, 0,  0, 127);
            imagefill($im1, 0, 0,  $color);
            imagesavealpha($im1, true);

            imagealphablending($im2, false);
            $color = imagecolorallocatealpha($im2, 0, 0,  0, 127);
            imagefill($im2, 0, 0,  $color);
            imagesavealpha($im2, true);

            imagealphablending($im3, false);
            $color = imagecolorallocatealpha($im3, 0, 0,  0, 127);
            imagefill($im3, 0, 0,  $color);
            imagesavealpha($im3, true);
        }
    } else {
        $im1 = imagecreate(100, 100);
        $im2 = imagecreate(35, 35);
        $im3 = imagecreate(512, 512);
    }

    $cx = $image->width / 2;
    $cy = $image->height / 2;

    if ($image->width < $image->height) {
        $half = floor($image->width / 2.0);
    } else {
        $half = floor($image->height / 2.0);
    }

    imagecopybicubic($im1, $im, 0, 0, $cx - $half, $cy - $half, 100, 100, $half * 2, $half * 2);
    imagecopybicubic($im2, $im, 0, 0, $cx - $half, $cy - $half, 35, 35, $half * 2, $half * 2);
    imagecopybicubic($im3, $im, 0, 0, $cx - $half, $cy - $half, 512, 512, $half * 2, $half * 2);

    $fs = get_file_storage();

    $icon = array('contextid'=>$context->id, 'component'=>$component, 'filearea'=>$filearea, 'itemid'=>$itemid, 'filepath'=>'/');

    ob_start();
    if (!$imagefnc($im1, NULL, $quality, $filters)) {
        // keep old icons
        ob_end_clean();
        return false;
    }
    $data = ob_get_clean();
    imagedestroy($im1);
    $icon['filename'] = 'f1'.$imageext;
    $fs->delete_area_files($context->id, $component, $filearea, $itemid);
    $file1 = $fs->create_file_from_string($icon, $data);

    ob_start();
    if (!$imagefnc($im2, NULL, $quality, $filters)) {
        ob_end_clean();
        $fs->delete_area_files($context->id, $component, $filearea, $itemid);
        return false;
    }
    $data = ob_get_clean();
    imagedestroy($im2);
    $icon['filename'] = 'f2'.$imageext;
    $fs->create_file_from_string($icon, $data);

    ob_start();
    if (!$imagefnc($im3, NULL, $quality, $filters)) {
        ob_end_clean();
        $fs->delete_area_files($context->id, $component, $filearea, $itemid);
        return false;
    }
    $data = ob_get_clean();
    imagedestroy($im3);
    $icon['filename'] = 'f3'.$imageext;
    $fs->create_file_from_string($icon, $data);

    return $file1->get_id();
}

/**
 * Generates a thumbnail for the given image
 *
 * If the GD library has at least version 2 and PNG support is available, the returned data
 * is the content of a transparent PNG file containing the thumbnail. Otherwise, the function
 * returns contents of a JPEG file with black background containing the thumbnail.
 *
 * @param string $filepath the full path to the original image file
 * @param int $width the width of the requested thumbnail
 * @param int $height the height of the requested thumbnail
 * @return string|bool false if a problem occurs, the thumbnail image data otherwise
 */
function generate_image_thumbnail($filepath, $width, $height) {
    global $CFG;

    if (empty($CFG->gdversion) or empty($filepath) or empty($width) or empty($height)) {
        return false;
    }

    $imageinfo = getimagesize($filepath);

    if (empty($imageinfo)) {
        return false;
    }

    $originalwidth = $imageinfo[0];
    $originalheight = $imageinfo[1];

    if (empty($originalwidth) or empty($originalheight)) {
        return false;
    }

    $original = imagecreatefromstring(file_get_contents($filepath));

    if (function_exists('imagepng')) {
        $imagefnc = 'imagepng';
        $filters = PNG_NO_FILTER;
        $quality = 1;
    } else if (function_exists('imagejpeg')) {
        $imagefnc = 'imagejpeg';
        $filters = null;
        $quality = 90;
    } else {
        debugging('Neither JPEG nor PNG are supported at this server, please fix the system configuration.');
        return false;
    }

    if (function_exists('imagecreatetruecolor') and $CFG->gdversion >= 2) {
        $thumbnail = imagecreatetruecolor($width, $height);
        if ($imagefnc === 'imagepng') {
            imagealphablending($thumbnail, false);
            imagefill($thumbnail, 0, 0, imagecolorallocatealpha($thumbnail, 0, 0, 0, 127));
            imagesavealpha($thumbnail, true);
        }
    } else {
        $thumbnail = imagecreate($width, $height);
    }

    $ratio = min($width / $originalwidth, $height / $originalheight);

    if ($ratio < 1) {
        $targetwidth = floor($originalwidth * $ratio);
        $targetheight = floor($originalheight * $ratio);
    } else {
        // do not enlarge the original file if it is smaller than the requested thumbnail size
        $targetwidth = $originalwidth;
        $targetheight = $originalheight;
    }

    $dstx = floor(($width - $targetwidth) / 2);
    $dsty = floor(($height - $targetheight) / 2);

    imagecopybicubic($thumbnail, $original, $dstx, $dsty, 0, 0, $targetwidth, $targetheight, $originalwidth, $originalheight);

    ob_start();
    if (!$imagefnc($thumbnail, null, $quality, $filters)) {
        ob_end_clean();
        return false;
    }
    $data = ob_get_clean();
    imagedestroy($original);
    imagedestroy($thumbnail);

    return $data;
}
